Thermally stable polyester fibers having improved dyeability and dye lightfastness

ABSTRACT

Modified polyester filaments having over conventional filaments, improved inherent thermal stability in the presence of oxygen and inherent disperse dye uptake, without the significant loss in dye lightfastness typical of such modified filaments, are produced from terephthalic acid; glycols; small amounts of mixtures of compounds having a typical general formula: R-O(G-O)x-H, where R is an alkyl group containing an average of from about eight to 20 carbon atoms; G is a hydrocarbon radical selected from the group consisting of ethylene, propylene, and isomers thereof, butylene and isomers thereof, and mixtures of the above; and x has an average value of from 8-20, and is about equal to 8-greater than R; and small amounts of manganous ion. Polyfunctional chainbranching agents in amounts up to about 0.7 mole percent, based on the weight of the dicarboxylic acid or ester-forming derivative thereof, may be added, whereby the polymer, with the chain terminators described above, can be polymerized to higher molecular weights by ordinary polymerization techniques.

United States Patent King et al. 1 June 6, 1972 [541 THERMALLY STABLEPOLYESTER 3,042,656 7/1962 Frey ..260/77 FIBERS HAVING [IMPROVED3,223,752 12/1965 Tate et al ..260/873 Y ABILITY AND DYE 3,461,468 8/1969 Morgan et al. ..760/75 T LIGHTFASTNESS Primary Examiner-MelvinGoldstein [72] Inventor Henr L, Kin Eugene L, Ri ld, b h Attorney-ThomasY. Awalt, Jr., Roben L. Broad, Jr., Neal E.

of Cary, N.C.; James C. Randall, Bart- Willis and Elmer Fischerlesville, Okla.

57 ABSTRACT [73] Assignee: Monsanto Company, St. Louis, Mo. 1 [22] F xeov 3 19 Modified polyester filaments having over conventional fila-Appl. No.: 873,333

Related US. Application Data [63] Continuation-in-part of Ser. No.824,092, May 13, 1969, and a continuation-in-part of Ser. No. 789,528,

Jan. 7, 1969, abandoned.

52 us. Cl. ..260/77, 8/DIG. 4 [51] Int. Cl ..C08g 17/08 [58] Field ofSearch ..260/77 [56] References Cited UNlTED STATES PATENTS 2,556,2956/1951 Pace ..260/75 X 2,895,946 7/1959 Huffman ..260/75 2,905,657 9/ l959 Huffman l ..260/75 3,033,824 5/1962 Huffman ..260/75 ments, improvedinherent thermal stability in the presence of oxygen and inherentdisperse dye uptake, without the significant loss in dye lightfastnesstypical of such modified filaments, are produced from terephthalic acid;glycols; small amounts of mixtures of compounds having a typical generalformula: RO[GO],H, where R is an alkyl group containing an average offrom about eight to 20 carbon atoms; G is a hydrocarbon radical selectedfrom the group consisting of ethylene, propylene, and isomers thereof,butylene and isomers thereof, and mixtures of the above; and x has anaverage value of from 8-20, and is about equal to S-greater than R; andsmall amounts of manganous ion. Polyfunctional chain-branching agents inamounts up to about 0.7 mole percent, based on the weight of thedicarboxylic acid or ester forming derivative thereof, may be added,whereby the polymer, with the chain terminators described above, can bepolymerized to higher molecular weights by ordinary polymerizationtechniques.

3 Claims, 3 Drawing Figures MICRO MOLES OF HCHO m O 5 IO I5 20 25 3O--N0.0F E O UNITS LOSS OF FORMALDEHYDE OF VARIOUS ETHYLENE OXIDEPOLYETHERS FIG. I.

DISPERSE DYEABILITY AS A FUNCTION OF R FIG. 2.

/o DYE (ON WEIGHT OF FIBER) N N 01 0 4 8 l2 I6202428 32 DISPERSEDYEABILITY AS A FUNCTION OF X I F I 6.. 3. HENRY T5752 DYE (ON WEIGHT OFFIBER) EUGENE L.RINGWALD JAMES C. RANDALL ATTORNEY BACKGROUND OF THEINVENTION This invention relates to polyesters produced by condensationreactions of polymethylene glycols and dicarboxylic acids 'or reactivederivatives thereof. .It is well known that some polymeric polyestersprepared by the condensation of a glycol or its functional derivativesand a dicarboxylic acid or a polyester-fomn'ng derivative thereof, suchas an acid halide, a salt, or a simple-ester of a dibasic acid andvolatile monohydric alcohol are excellent fiber-fonning polymers.Commercially, high polymeric polyesters are prepared, for example, bythe condensation of terephthalic acid or dimethyl terephthalate and apolymethylene glycol containing from about two to carbon atoms. Thesepolyesters are relatively insoluble, chemically inactive, hydrophobicmaterials capable of being formed into filaments which can be cold-drawnto produce textile fibers of superior strength and pliability. However;since these materials are not readily permeable to water, they cannot besatisfactorily dyed by ordinary dyeing procedures.

- The compact structure of polyethylene terephthalate fibers, forexample, the molecules of which are closely packed along the axis ofthe-fibers, makes it quite difficult, except with a limited number ofdyes, to obtain a high degree of dyebath exhaustion or to securesatisfactory deep shades. Absorption and penetration of the dye into thefiber core are limited by the inherent properties of the fiber.

- A number of methods have been proposed to increase the dyeability ofpolyesters, and particularly polyethylene polyesters having improveddyeability. Thermally stable polyesters with improved dyeability wouldhave significant commercial and practical value and utility.

Our co-pending application, Ser. No. 824,092, filed May 13, 1969,describes the use of small amounts of compounds having a typical generalformula: RO[G--O],H where R is an alkyl group containing an average offrom about eight to carbon atoms; G is a hydrocarbon radical selectedfrom the group consisting of ethylene, propylene and isomers thereof,butylene and isomers thereof, and mixtures of the above; and x has anaverage value of from 8-20, and is about equal to or greater than R.These modified polyester compositions are prepared by reacting anaromatic dicarboxylic acid, the polymethylene glycol and a small amountof the glycol additive under polyesterification conditions until afiber-forming polymeric polyester composition is obtained. Small amountsof a chain-branching agent may also be added to the reaction as desired.These modified polyester compositions are useful 'in the production ofshaped articles by extrusion, molding, or casting in the nature ofyarns, fabrics, films, pellicles, bearings, ornaments, or the like. Theyare particularly useful'in the production of thermally stable textilefibers having improved dyeability, particularly with disperse dyes. Onedifficulty encountered in the use of such modified polyesters lies inthe fact that the substrate alone, as well as the dyed substrate has aninferior lightfastness as compared with a filament comprised ofsubstantially unmodified polyester filament produced under otherwisesimilar conditions.

Theoretically, this inferior lightfastness occurs by way of absorptionof energy at the site in the polymer where spectral characteristics canbe slightly modified by a fiber morphology, e.g., the site of the glycoladditive. This energy is then transferred to oxygen and possibly watermolecules resulting in the formation of peroxides. This hydroperoxideformation in the polymer is primarily dependent upon the glycoladditive, although to a lesser extent, any diethylene glycol present,ultimately leads to oxidative degradation of the dye molecules.

SUMMARY OF THE INVENTION It is an object of this invention to provide amodified polyester filament having the inherent superior thermal sta-'bility in oxygen or air and disperse dye uptake characteristic of themodified polyesters described in our co-pending appliin oxygen anddisperse dye uptake characteristic of these modified polyesterfilaments.

Briefly, the objects of this invention are accomplished by preparing afiber-forming polyester from a dicarboxylic acid and a glycol andcontaining in the polymer molecule a small amount of compounds having atypical general formula: R

O[GO] ,-l-l, where R is an alkyl group containing an average of fromabout eight to 20 carbon atoms; G is a hydrocarbon. radical selectedfrom the group consisting of ethylene, propylene and isomers thereof,butylene and isomers thereof, and mixtures of the above; and x has anaverage value of from 8-20, and is about equal to or greater than R.Mixtures of these glycols may also be used. The alkoxy glycol additivemay be used at concentrations of between about 0.25 and 3 mole percent,based on the weight of the dicarboxylic acid or ester-forming derivativethereof or on each polyester repeating unit; Preferably, the alkoxyglycol additive is present in an amount of from about 0.75 to 2 molepercent, based on the weight of the dicarboxylic acid or esterformingderivative thereof or on each polyester repeating unit. The use of lessthan 0.25 mole percent of the alkoxy glycol additive does not givesignificant improvement in the dyeability in the final product, and whenmore than 3 mole percent of the additive is employed, undesirablequantities of chainbranching agents are necessary to counteract thetendency of the monohydroxyl additive to restrict the buildup ofmolecular weight in the final polymeric product. ln addition to thealkoxy glycol additive, small amounts o'f manganous ion are added in theform of a salt which is believed to act as a quencher" for the excitedtriplet state of dye molecules in order to prevent dye degradation. Itis also believed that the use of the manganous ion also tends tostabilize the polymer substrate, or the alkoxy glycol additive portionthereof, so that heat stability, maintenance of strength, and whitenessof the substrate are also improved.

To further understand the invention, reference will be made to theattached drawings that form a part of the present invention:

FIG. 1 is a graph showing the amount of formaldehyde loss at C. for 60minutes of alkoxy polyethylene glycols varying in the number of ethyleneoxide units present in the molecules;

FIG. 2 is' a graph showing the relative disperse dyeability in terms ofpercentage of the dye, based on the weight of the fiber, of polyesterfibers modified with alkoxy polyethylene glycols in which the carbonatoms in the alkoxy group represented by R in the general formula, wasvaried between four and 20, with the number of ethylene oxide units (x)coristant at a value of 12-14; and

FIG. 3 is a graph showing the relative disperse dyeability in terms ofpercentage of dye on the weight of the fiber, of polyester fibersmodified with an alkoxy polyethylene glycol in which the number ofethylene oxide units (at) was varied from DESCRIPTION OF THE PREFERREDEMBODIMENTS The synthetic linear condensation polyesters contemplated inthe practice of the invention are those formed from dicarboxylic acidsand glycols, and copolyesters or modifications of these polyesters andcopolyesters. In a highly polymerized condition, these polyesters andcopolyesters can be formed intotilaments and the like and subsequentlyoriented permanently by drawing. Among the polyesters and copolyestersspecifically useful in the instant invention are those resulting fromheating one or more of the glycols of the series HO(CH ),,Ol-1, in whichn is an integer from 2 to 10, or cycloaliphatic glycols with one or moredicarboxylic acids, or ester-forming derivatives thereof. Among thedicarboxylic acids and ester-forming derivatives thereof useful in thepresent invention there may be named terephthalic acid, isophthalicacid, p,p'-dicarboxybiphenyl, p,p'-dicarbox; ydiphenylsulfone, p,p'dicarboxydiphenylmethane, and the aliphatic, cycloalphatic, and arylesters and half-esters, ammonium and amine salts, and the acid halidesof the abovenamed compounds, and the like. Examples of the polyhydricalcohols which may be employed in practicing the instant invention areethylene glycol, trimethylene glycol, tetramethylene glycol, andcyclohexane dimethanol, and the like. Polyethylene terephthalate,however, is the preferred polymer because of the ready availability ofterephthalic acid or dimethyl terephthalate and ethylene glycol, fromwhich it is made. it also has arelatively high melting point of about250 C. through 265 C., and this property is particularly desirable inthe manufacture of filaments in the textile industry.

Additives which are an essential part of this invention includecompounds having a typical general formula: RO[G O],H, where'R-is analkyl group containing an average of from about eight to 20 carbonatoms; G is a hydrocarbon radical selected from the group consisting ofethylene, propylene and isomers thereof, butylene and isomers thereof,and mixtures of the above; and x has an average value of from 8-20 andis about equal to or greater than R. By average is meant that the alkoxyglycol additive may comprise mixtures of the alko'xy glycol with somevariances from the figures shown; but that theaverage of the integers inthe mixture will be as indicated. Preferably, the .R group contains 1216carbon atoms. The optimum degree f-polymerization (x) is about 12-16.This additive may be used at concentrations of from about 0.25 to 3 molepercent, based on the weight of the dicarboxylic acid or ester-formingderivative thereof or on each polyester repeating unit. Preferably, theadditive is present in amounts of from about 0.75 to 2 mole percent,based on the weight of the dicarboxylic acid or ester-forming derivativethereof or on each polyester repeating unit.

- The use of alkoxy polyethylene glycols as chain-terminators in thepreparation of modified polyesters is not new (see, for example, U.S.Pat. No. 2,905,657). Whatis new and significant, with respect to theparticular glycols described, is that within the described criticalrange of the alkyl group there is a surprisingly and substantially lowerdegree of autoxidation which takes place at elevated temperatures (aslow as 150 C.). Moreover, there are new and distinguishable dyeabilityfactors involved.

Autoxidation is the phenomenon which is responsible for much of ourenvironmental chemistry. it is involved in the ageing of fats and oils,drying of paints, and degradation of natural andsynthetic fibers. Theprocesses involved may be catalyzed by heat or light and are freeradical by nature. Generally speaking, autoxidation proceeds by freeradical, chain mechanisms; peroxy radicals and hydroperoxide groups areformed which'are precursors to other products. Typical products fromautoxidation processes are alcohols and carbonyl-containing compounds.Chain-terminating reactions significantly affect the rates ofautoxidation processes.

The products observed from the autoxidation of alkoxy polyethyleneglycols are principally alcohol and formate ester chain-terminal groupsand formaldehyde, carbon dioxide, and water. Formaldehyde is a majorvolatile product. As above stated, significant and surprisingdifferences in thermal stability in the presence of oxygen have beenobserved among the various alkoxy polyethylene glycols. The type ofalkoxy unit and the degree of polymerization are apparently related tothe susceptibility of autoxidation.

It has been found, for example, that as the number of carbon atoms inthe alkoxy end group (R) is increased beyond the methoxy (with degree ofpolymerization held constant) there is a surprising degree in the amountof formaldehyde evolved when the glycol additive is heated in a sweep ofair at 193 C., until the alkoxy group'reaches eight carbon atoms, afterwhich there is a leveling off. Further increase beyond eight to 14carbon atoms in the alkoxy group causes no appreciable difference in theheat stability of the glycol. Exemplifying the above, alkoxy terminatedpolyethylene glycol polymers having the structural formula: R(OCH CH OHwere subjected to the above-described conditions, and

liberated formaldehyde in accordance with the following table. I

"ulkoxy polyethylene glycol prepared from mixture of 14 and 15 carbonalcohols.

It was also discovered that when these same alkoxy glycols were used aschain terminators in the production of modified polyesters, the heatstability effect was carried over to the polyester fiber.

On the other hand, where the number of carbon atoms in the alkoxy endgroup was held constant at about 14 and the degree of polymerization ofthe polyether chain was increased, the compounds being heated in a sweepof air at 195 C., for 80 minutes, there was a marked increase in thenumber of micromoles of formaldehyde released as the degree ofpolymerization (number of ethylene oxide units) was increased from aboutfive to 30, indicating a decrease in heat stability of the alkoxy glycolas shown by FIG. 1. Therefore, so far as heat stability alone isconcerned, and ignoring any possible effect of the relationship of thedegree of polymerization to the length of the alkoxy end groups, itappears that an alkoxy poly(oxyalkylene) glycol as described above whereR is an alkyl group containing no less than eight carbon atoms, and withan extremely low degree of polymerization would be optimum.

As stated above, however, dyeability of the modified polymer is anextremely important factor so far as the use of these additives isconcerned. in FIG. 2, the effect on fiber dyeability of changes in thenumber of carbon atoms in the alkoxy group (R) with the degree ofpolymerization (x) being held constant at 11-13 is shown; and in FIG. 3,the effect of changes in the degree of polymerization (x) with R beingheld constant at 14.5 is shown. FIGS. 2 and 3 show the dispersedyeability of these compounds in terms of percent dye on the weight ofthe fiber, dyeing being accomplished as explained in Example 1. It willbeobserved from FIG. 2 that there is a tendency toward decreaseddyeability as the number of carbon atoms in the alkoxy end group of theadditive increased. FIG. 3 shows a substantial increase in dyeability asthe degree of polymerization (x) is increased from about 4 to about12-14. and thereafter a decrease in dyeability.

A minimum optimum value of eight representing the number of carbon atomsin the alkoxy end groups has thus been established on the basis of heatstability, and a maximal optimum value of 20 has been established beyondwhich there is no substantial increase in heat stability, but there is acorresponding decrease in disperse dyeability (FIG. 2).

The degree of polymerization has been established on the basis ofdyeability with about eight as a minimally marginal value and 20 as amarginally maximum value (FIG. 3), with decreasing heat stability acrossthe range (FIG. 2). An additional limiting factor involving therelationship of R to x will be developed in the examples.

The precise structure of G is not considered critical in that theinstant invention except insofar as it must exclude the alkoxy (polyoxymethylene) glycols which depolymerize under polyester polymerizationconditions. We have found that the alkoxy poly( oxyethylene), alkoxypoly(oxypropylene), and alkoxy poly(oxytetramethylene) glycols(including copolymers and block copolymers) and mixtures thereof producegood results in accordance with this invention. 7

The above can be partially explained in terms of inhibition of furtherautoxidation by products formed from the terminal alkoxy groups in theinitial stage of oxidation. Those derived from short alkyl chains arevolatile at the test temperature, and escape without acting asinhibitors.

When the additive contains an alkoxy group which is an effectiveinhibitor of autoxidation, the number of alkyleneoxy units in thepolyether additive becomes significant. It has been found that chainshaving more than about 25 units are not adequately stable. This isbelieved to result from the low concentration of the inhibiting terminalalkoxy group in such a chain. On the other hand, a low number ofalkyleneoxy units per molecule results in an excessive number of chainterminations when an adequate weight of the modifier is added to achievethe desired dyeability. Poor processibility results from excessive chaintermination.

Since the hydrophobic alkyl portion of the additive makes very little,if any, contribution to the enhanced dyeability, it is desirable that amajor portion of the molecule be comprised of the hydrophilic polyetherchain. Thus, alkoxy poly(oxyalkylene) glycols in which the number ofoxyalkylene groups is about equal to or greater than the number ofcarbon atoms in the alkyl group, resulting in a polymer composed of morethan seventy percent by weight of the hydrophilic polyether portion, aswill be shown in the examples, are most effective (see Table III).Included within the meaning of about equal," as used herein, is :2;

The second additive to the polymerization mix which is essential to thisinvention is the manganous ion in the form of a salt such as acetate,formate, terephthalate, succinate, and adipate. It has been found thatin amounts of 10-500 parts per million of Mn ion and preferably 50-150parts per million of Mn, based on the weight of the acid and glycol,dyed lightfastness in the filament product is-substantially improved.Where amounts are used in excess of about 200-300 ppm, the product maybe somewhat colored by the additive.

If desired, the modified polyesters of this invention may containchain-branching agents, which, as taught in US. Pat.

' No. 2,895,946, are employed to increase the viscosity or molecularweight of the polyesters, such as polyols which have a functionalitygreater than two; that is, they contain more than two functional groups,such as hydroxyl.

The chain-branching agents may be employed in the preparation of thepolyester and copolyesters in amounts ranging from 0 mole percent to 0.7mole percent, based on the amount of dicarboxylic acid or ester-formingderivative thereof employed in the reaction mixture. If thechainbranching agent is tetra-functional, as for example,pentaerythritol, quantities not in excess of 0.45 mole percent should beused. The preferred concentration of a tetra-functional chain-branchingagent is about 0.2 mole percent. If a tri-functional chain-branchingagent, such as for example, trimesic acid, is used, somewhat more isrequired for results equivalent to that of the tetra-functionalchain-branching agent, and amounts up to 0.7 mole percent may be used.The preferred concentration of a tri-functional chain-branching agent is0.5 mole percent.

In the practice of this invention, the dibasic acid or esterformingderivative thereof, the glycol, the alkoxylpolyoxylalkaline glycol, andthe manganese salt are charged to the reaction vessel at the beginningof the first stage of the esterification reaction, and the reactionproceeds as in well-known esterification polymerization. If desired, thechain-branching agent may also be charged to the reaction vessel at thistime.

When preparing the polyester from an ester, such as dimethylterephthalate, the first stage of reaction may be carried out at to C.and'at a pressure ofO to 7 p. s. i. g. If the polyester is prepared fromthe acid, such as terephthalic acid, the first stage of reaction may becarried out at about 220 to 260 C. and at pressures of from atmosphericto about 60 p. s. i. g. The methanol or water evolved during the firststage of reaction is continuously removed by distillation. At thecompletion of the first stage, the excess glycol, if any, is distilledoff prior to entering the second stage of the reaction.

In the second or polymerization stage, the reaction may be conducted atreduced pressures and preferably in the presence of an inert gas, suchas nitrogen, in order to prevent oxidation. This can be accomplished bymaintaining a nitrogen blanket over the reactants, the blanketcontaining less than 0.033 percent oxygen. For optimum results, apressure within the range of less than 1 mm. up to 5 mm. of mercury isemployed. This reduced pressure is necessary to remove the free ethyleneglycol that is formed during this stage of the reaction, the ethyleneglycol being volatilized under these conditions and removed from thesystem. The polymerization step is conducted at a temperature in therange of 220 to 300 C. This stage of the reaction may be effected eitherin the liquid melt or solid phase. In the liquid phase, particularly,reduced pressures must be employed in order to remove the free ethyleneglycol which emerges from the polymer as a result of the condensationreaction.

Although the process of this invention may be conducted stepwise, it isparticularly adaptable for use in the continuous production ofpolyesters. In the preparation of the described polyesters, the firststage of the reaction takes place in approximately three-fourths to 2hours. The use of an ester-interchange catalyst is desirable whenstarting with dimethyl terephthalate. In the absence of a catalyst,times up to 6 hours may be necessary in order to complete this phase ofthe reaction. In the polymerization stage, a reaction time ofapproximately 1 to 4 hours may be employed with a time of 1 to 3 hoursbeing the optimum, depending on catalyst concentration, temperature,viscosity desired, and the like.

The linear condensation polyesters, produced in accordance with thepresent invention, have specific viscosities in the order of about about0.25 to 0.6, which represent the fiberand filament-forming polymers. Itis to be understood, of course, that nonfiber-forming polyesters may beproduced by means of the present invention, which have a greater or lessmelt viscosity than that specified above.

Specific viscosity as employed herein, is represented by the formula:

Nsp

' a solution containing 0.5 percent by weight of the polymer dissolvedin a solvent mixture containing two parts by weight of phenol and onepart by weight of 2,4,6-trichlorophenol, based on the total weight ofthe mixture is employed.

The polyesters of this invention may be produced to form filaments andfilms by melt-spinning methods and can be extruded or drawn in themolten state to yield products that can be subsequently cold-drawn tothe extent of several hundred percent of their original lengths, wherebymolecularly oriented structures of high tenacity may be obtained. Thecondensation product can be cooled and comminuted followed by subsequentremelting and processing to form filaments, films, molded articles, andthe like.

Alternatively, the polyesters of this invention may be processed toshaped objects by the wet-spinning method, wherein the polyesters aredissolved in a suitable solvent and the resulting solution is extrudedthrough a spinnerette into a bath composed of a liquid that will extractthe solvent from the solution. As a result of this extraction, thepolyester is coagulated into filamentary material. The coagulatedmaterial is withdrawn from the bath and is then generally subjected to astretching operation in order to increase the tenacity and to inducemolecular orientation therein. Other treating and processing steps maybe given the oriented filaments.

If it is desired to produce shaped articles from the polyesters of thepresent invention which have a modified appearance or modifiedproperties, various agents may be added to the polyester prior to thefabrication of the articles or those agents may be incorporated with theinitial reactants. Such added agents might be plasticizers, antistaticagents, fire-retarding agents, stabilizers, and the like.

To further illustrate the present invention and the advantages thereof,the following specific examples are given, it being understood thatthese are merely intended to be illustrative and not limitative. Unlessother wise indicated, all parts and percents are by weight.

The following procedure was used to prepare the polymers in theexamples. The charge was added directly to a standard polyesterautoclave and the system was purged six times with nitrogen, allowingthe pressure to rise to 150 p.s.i.g., and then releasing it slowly toatmos heric pressure each time.

Heat was then applied to the closed system, and when the temperatureinside the autoclave had reached 100 to 125 C., the stirrer was started.When the temperature of the outside wall of the autoclave had reachedabout 250 C. (the inside temperature being about 230 to 235 C. and thepressure being about 25 p.s.i.g.), the off-vapor valve was adjusted tomaintain these conditions of temperature and pressure. As the firstdistillate containing water and some ethylene glycol appeared, theesterification stage was considered to have started. The stirrer speedwas set at 240 rpm. This esterification step usually took from about 40to 60 minutes for completion, after which the pressure of the system wasadjusted to atmospheric pressure. The heating rate was then increaseduntil the temperature reached about 280 C. During this time, excessethylene glycol was distilled off. An ethylene glycol slurry of titaniumdioxide was introduced through an injection port when the insidetemperature had reached about 260 to 265 C. Then the inside temperaturewas raised to about 280 C., the pressure was maintained at less than 2mm. Hg and the polymerization continued until a polymer having aspecific viscosity in the fiber-forming range between 0.30 to less thanabout 0.4 was formed. The polymer was extruded through a spinnerette,and the filaments obtained were drawn about five times their originallength over a hot pin at about 80 C.

The dyeing test used in Examples 1-8 was as follows. Fiber samples ofabout 3 denier were scoured and dried. One-half gram of fiber and 20 ml.of dye solution were placed in a small glass tube capable ofwithstanding internal pressure. The dye solution was prepared by mixing250 mg. of a disperse dye and 0.5 gram of a commercial dispersing agentin a 250 ml. volmetric flask together with an amount of deionized watersufficient to fill the flask to the mark. The dye tubes were placed in arotating rack held within a steam bath, and rotated for two hours at atemperature of about 210 F. The tubes were then quickly quenched in ice,and 5 ml. aliquots were pipeted into 50 ml. volumetric flasks which werethen filled with dimethylformamide. The optical density of each solutionwas measured O.D. Blank-O.D. Sample O.D. Blank original dyeconcentration dye uptake (0. w. f.)

(where O.D. optical density) During the processing of polyesterfilaments, staple, blends, fabric, and the like, heating at varioustemperatures for various periods of time is often necessary, e.g.,polyester fabrics may be subjected to temperatures of 175 C. or higherfor periods of up to 10 minutes or more. The following thermal stabilitytests were run where indicated. A 5-gram sample of the polyester wasfluffed into a ball, placed in an aluminum cup into which about IOr-inchholes had been punched, and the ball was heated for 10 minutes at 175 C.in a circulatingair oven, often with a thermocouple held at the centerof the ball.

EXAMPLE 1 The autoclave was charged with 166 grams of terephthalic acid,440 ml. of ethylene glycol, 0.078 gram of lithium sulfate, 0.967 gram ofantimony trioxide, 0.20 gram of pentaerythritol, and 10 grams ofmethoxypolyethylene glycol having an average molecular weight of about550. Polymer and fiber were prepared following the procedure describedabove.

The fiber took up 2.2 percent 0. w. f. of Latyl Brilliant Blue 26 dye(C.l. Disperse Blue 61). Unmodified polyethylene terephthalate took up0.6 percent 0. w. f. of this dye.

The fiber fused severely when heated at 175 C. for 10 minutes, thethermocouple within the carded ball recording at a temperature of 220 C.

EXAMPLES 2-8 Example 2 The autoclave was charged with grams terephthalicacid, 330 ml. ethylene glycol, 0.04 grams lithium acetate, 0.1 gramsantimony glycoloxide, 0.3 gram pentaerythritol, and 8.0 grams of thereaction product of 4 molar equivalents of ethylene oxide with anapproximately equimolar mixture of straight chain alcohols having 14 to15 carbon atoms. Polymer and fiber were prepared following the proceduredescribed in Example 1. Examples 3-8 were conducted in the same manneras Example 2 with the exception that the amounts of pentaerythritol usedin each example were as follows: Example 3 0.15 grams; Example 4 0.2grams; Example 5 0.25 grams; Example 6 0.25 grams; Example 7 0.25 grams;and Example 8 0.00 grams. The alkoxy poly(oxyalkylene) glycols used hadthe general formula: ROICH CH O| .--H for which the number of carbonatoms in the alkyl group R and the degree of polymerization of ethyleneoxide (x) are shown in Table 11. The resulting percent dye uptake isshown for each sample.

The above results further substantiate the data shown in FIGS. l-3 andestablish the relationship between R and x which is theorized above.Example 4 was tested for heat stability and resisted fusion when heatedat C. for 10 minutes.

The Xenon-Arc lamp exposure used in Examples 9-12 was as described asAATCC 16E-l96. Reflectance readings of undyed substrates were generallyin accordance with AATCC 1 l I964.

EXAMPLE 9 The specified procedure was followed except that no glycoladditive and no manganese was used in the run. The autoclave was chargedwith 166 grams of terephthalic acid, 400 milliliters of ethylene glycol,0.078 gram of lithium sulfate, 0.967 gram of antimony trioxide, and 0.20gram of pentaerythritol. Knit tubings were prepared from the filaments(3) denier) and given a Varsol scour; then disperse dyed with variousdye combinations to six different shades shown at Table 111. The shadeswere considered typical, two being light, two being medium, and twobeing heavy. Tubings were then exposed to the Xenon-Arc Fade-Ometer for20, 40 and 80 SFH. The undyed tubings were exposed for 20 and 40 SFH.

EXAMPLE l0 Tubings were prepared as described in Example 9, except thatthe charge included a glycol additive having the formula: R-O[G)],-H, Rbeing an alkyl group containing an average of 14-15 carbon atoms, Gbeing an ethylene radical,

and 1 being about 14. The alkoxy glycol additive was present in anamount of 1.2 mole percent.

EXAMPLE 1 l EXAMPLE 12 The same procedure was used as in Example 10,except that 100 parts per million of manganese ion in the form ofmanganese acetate was included in the charge.

TABLE 111 Dyed Lightfastness Xenon-Arc Fade-Ometer Example 20 SFH 4O SFH80 SFH Beige 4 lt. 34 It. 3 lt. 3-4 It. 3 It. 2 lt. 1 l 4 1t. 3-4 It.2-3 lt. l2 4 1t. 3 lt. 2-3 lt. Light Blue 9 4 lt. 3-4 lt. 3-4 1t. 10 3It. 21t. 1-21t. 1 1 4 It. 3-4 It. 3 It. 12 34 lt. 3 lt. 2-3 lt. MossGreen 9 3-4 lt. 2-3 It. 2 1t. 10 v 3 lt. 2-3 1t. 2 lt. 11 4 1t. 3-4 lt.2-3 It. 12 4 1t. 3 lt. 2 lt. Gold 9 3-4 lt. 3 1t. 2-3 1t. 10 3-4 1t. 34lt. 2-3 1t. 1 1 3-4 lt. 3 It. 2-3 lt. l2 4 lt. 3-4 It 2-3 It. Olive 9 41t. 4 lt. 341:. 10 4 lt. 3-4 It. 3 It. I l 3- 4 lt. 34 It. 3-4 lt. 12 4lt. 34 lt. 3-4 It. Navy 3-4 It. 3 It.

10 41t. 3-4 lt. 3-4 lt. rd. 1 1 4 lt. 3-4 It. 34 It. rd. 12 3-4 d1. 3-4dl. 3-4 dl.

1t.=l1ght dl.==dul1 rd.=red 7 TABLE IV UNDYED LIGHTFASTNESS Color-EyeReflectometer A Values Example Lightness(Y) Purity DWL AY AP Unexposed 984.5 2.1 479 10 81.2 1.6 471 l 1 81.9 0.6 489 12 83.5 0.6 480 Exposed 20SFH 9 85.0 2.4 475 +0.5 +0.3 10 81.8 1.1 476 +0.6 0.5 11 82.3 1.3 473+0.4 +0.7 12 83.8 1.6 470 +0.3 +1.0 Exposed 40 SFH Example 10 (Table111) shows the inherent inferior dyed lightfastness of the modifiedpolyester. Examples 11 and 12 show how this inherently poor dyedlightfastness is improved to nearly that of the substantially unmodifiedpolyester. The dyed lightfastness of the sample containing 100 parts permillion of the manganese ion retained not less than about 3.8 at 20 SFH3.2 at 40 SFH, and 2.7 at SFH according to average Gray Scale values.The undyed lightfastness values of Table IV show comparable whitenessretention in the undyed fibers.

It is to be understood the changes and variations may be made in thepresent invention without departing from the sphere and scope thereof asdefined in the appended claims.

We claim:

1. A new composition of matter consisting essentially of a fiber-formingdisperse dyeable thermally stable linear condensation polyester havinginherent dyed lightfastness qualities, consisting of at least percent byweight of an ester of a glycols selected from HO(Cl-1 )nOl-1, in which nis an integer from 2 to 10, and cyclohexanedimethanol and terephthalicacid, and modified with from 0.25 to 3 mole percent, based on the weightof the terephthalic acid, of a chain terminating additive having ageneral formula: RO[GO] ,H, where R is an alkyl group containing abouteight to 20 carbon atoms; G is a hydrocarbon radical selected from thegroup consisting of ethylene, propylene and isomers thereof, andbutylene and isomers thereof; and x is an integer having a value 8-20.and is about equal to or greater than the number of carbon atoms in R;and including about 10-500 parts per million, based on the weight of theacid and glycol, of manganous ion.

2. The new composition of matter defined in claim 1 wherein the additivehaving the typical general formula R- O[G--O],-H is present in fromabout 0.75 to 2 mole percent, based on each polyester repeating unit, Ris an alkyl group containing an average of 12-16 carbon atoms, G is anethylene radical, and x has a value of 14.

3. A filament made from the composition of matter defined in claim 1.

2. The new composition of matter defined in claim 1 wherein the additivehaving the typical general formula R-O(G-O)x-H is present in from about0.75 to 2 mole percent, based on each polyester repeating unit, R is analkyl group containing an average of 12-16 carbon atoms, G is anethylene radical, and x has a value of
 14. 3. A filament made from thecomposition of matter defined in claim 1.